well they heard the noise but the RTE Engineer (Sent by BMW HQ) to inspect the car has declared it to be normal. They claimed to have compared it side by side with a brand new 335Is and the sound also appears in the new car. Just wanted to know if others out there have the same issue or they're all just bsin me.

Interesting. And you say this happens when the car is idling? I've never heard this sound before. Can you record the noise and post the video?